This invention relates to a technique for re-establishing permanent virtual circuits in a frame relay network in a rapid and efficient manner following a service outage.
Presently, several inter-exchange telecommunications carriers, such as ATandT, offer frame relay service for transporting data packets from one local area network to another. Among the customers that utilize frame relay service from ATandT and other telecommunications carriers are banks and financial institutions that transport data from automated teller machines and point of service terminals to data processing facilities to enable debiting of a purchaser""s account for cash withdrawals and debit-card purchasers. Other customers of frame relay service include manufacturers that use the service to transmit data among manufacturing facilities to coordinate scheduling, inventory levels, and other activities. Large retailers who maintain geographically separated stores and warehouses also use frame relay service to exchange data between facilities to assure timely delivery of merchandise.
The heavy reliance of customers on such frame relay service mandates that the carriers that offer such service provide fast restoration in the event of a service outage. Unfortunately, present day techniques for restoring service often take a significant amount of time, especially for very large networks. Invariably, in the event of a service outage, all of the Permanent Virtual Circuits (PVCs) that link frame relay switches become disabled, and must be re-established after isolation and repair of the fault. Reconnection of the PVCs requires re-establishment of logical (control) signaling links among the frame relay switches first before the frame relay switches can re-establish the PVCs themselves. During normal operation of a frame relay network, establishing such logical signaling links takes little time. However, in the event of a large service outage, a significant amount of activity often exists in the network, significantly lengthening the time required to re-establish the PVCs among the frame relay switches. As a consequence, customers incur delayed restoration of service, increasing customer dissatisfaction and reducing revenue to the carrier providing such service.
Thus, there is a need for a technique that reduces the time required to re-establish PVCs in a frame relay network following a service outage.
Briefly in accordance with a preferred embodiment of the invention, a method is provided for restoring Permanent Virtual Circuits (PVCs) that link frame relay switches in a frame relay network following a fault. Prior to the fault, a main configuration controller periodically polls each of the switches in the frame relay network to obtain information about the PVCs linking the switches. Such polling is done out-of band from the frame relay network, either via a dedicated IP control network, or via dial-up links of a Public Switched Telephone Network. The main configuration controller stores the information obtained during each polling by over-writing the information obtained during the previous polling. Following isolation and mitigation of a fault in the frame relay network, the main configuration downloads to each switch, via the out-of-band network, the stored PVC information to enable the frame relay switches to the switches to reestablish the PVCs quickly.